1. Field of the Invention
The present invention relates to an image forming apparatus such as copying apparatus, or printer in which a toner image formed on an image-bearing member is transferred onto a recording material by a transfer unit and an image is formed.
2. Description of the Related Art
In recent years, in an image forming apparatus for forming a toner image by an electrophotographic image forming process, improvement of image quality is required. As one of such requirements, there is a prevention of toner deposition onto a back surface of a recording material (transfer material).
For this purpose, a member for cleaning a transfer member for transferring the toner image formed on a photosensitive drum or an intermediate transfer belt onto the recording material has been provided. A method whereby a blade-shaped cleaning member comes into pressure contact with the transfer member has been used as a cleaning method. However, if the blade-shaped cleaning member comes into pressure contact with the transfer member, the transfer member is abraded.
As a method of cleaning the toner remaining on the intermediate transfer belt after the secondary transferring step, an electrostatic cleaning method of electrostatically removing the toner on the intermediate transfer belt has been proposed (refer to Japanese Patent Application Laid-Open No. 2002-229344). According to such a method, a conductive fur brush comes into contact with the intermediate transfer belt and rotated. A voltage-applied member such as a metal roller to which a voltage has been applied comes into contact with the conductive fur brush. Thus, the toner on the intermediate transfer belt is electrostatically adsorbed, thereby cleaning (electrostatic fur brush cleaning).
To reduce the abrasion of the transfer member, it has been tried to use the electrostatic fur brush cleaning in order to clean the transfer member.
However, when the cleaning of a transfer roller by the electrostatic fur brush cleaning is examined, it has been found that there are the following problems.
That is, if the cleaning is continuously executed, toner is accumulated to the fur brush, a function as a fur brush cannot be sufficiently effected, and there is a case where a back fouling of the transfer material is caused.